A today's data transfer system, for example, a server system, is designed to carry out the data transfer through the use of an optical signal while conducting the data processing by means of an electric signal. An optical module is employed for the data transfer using an optical signal in such a server system. The optical module is a device for making a connection and optical coupling between a photoelectric conversion element and an optical element such as an optical fiber for the propagation of an optical signal.
Concretely, a transmission module, which transmits an optical signal through an optical fiber, can be configured by making a connection between the photoelectric conversion element for the conversion of an electric signal into an optical signal and the optical fiber. While a reception module, which is made to receive an optical signal transmitted through an optical fiber, can be configured by establishing a connection between the photoelectric conversion element for the conversion of an optical signal into an electric signal and the optical fiber.
In addition, the assumption of a server system in the today's development is that a large number of optical modules are packaged in parallel for carrying out the large-scale optical signal parallel transmission. For this reason, the requirement for each optical module is a low dissipation power.
However, although high-speed response needs arise for an optical element along with an increase in data throughput, in a case in which the internal temperature of the optical element increases due to the heat generation resulting from high-speed operations of peripheral circuit elements and the heat generation stemming from the operation of the optical element itself, the optical power decreases. In such a situation, for ensuring the required optical power to be outputted from an optical module, further electric power consumption occurs under constraint.
The optical modules for use in communications, developed so far, have been designed in light of higher-efficiency coupling between an optical element and an optical fiber because of the requirement for the long-distance transmission. In many cases, the lens coupling has been put to use, for that it shows a relatively high coupling efficiency.
For example, as an optical module employing the aforesaid lens coupling, there has been known a can package type optical module shown in FIG. 17. This optical module 100 shown in FIG. 17 comprises a semiconductor optical element 101 and further includes two lenses 102, 103, a ferrule 104, a window-attached cap 105, a stem 106, a flexible wiring substrate 107 and a heat sink 108. That is, for the fixed connection between the semiconductor optical element 101 and the ferrule 104, there are used the two lenses 102, 103, the window-attached cap 105, the stem 106 and the flexible wiring substrate 107, while for the heat radiation of the heat generation at the semiconductor optical element 101, there is prepared the heat sink 108.
In the above-mentioned conventional optical module 100 shown in FIG. 17, the heat sink 108 is made of a material having a relatively high thermal conductivity and is located on a rear surface of the semiconductor optical element 101. The generated heat from the semiconductor optical element 101 is exhausted through this heat sink 108 toward the stem 106 mounting the semiconductor optical element 101, the flexible wiring substrate 107 and others.
In addition, as the techniques related to the invention of the subject application, there are the following Patent Documents 1 to 4.
Patent Document 1: U.S. Pat. No. 6,739,760
Patent Document 2: U.S. Pat. No. 6,863,444
Patent Document 3: Japanese Patent Laid-Open No. 2005-116990
Patent Document 4: Japanese Patent Laid-Open No. 2003-324233